High "Latch Free" Waits with Contention on 'Result Cache: RC Latch' when RESULT_CACHE_MODE = MANUAL on Oracle 12c
(Doc ID 2002089.1)
Last updated on MAY 28, 2019
Applies to:Oracle Database - Enterprise Edition - Version 126.96.36.199 to 188.8.131.52 [Release 12.1 to 12.2]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
- High numbers of waits for 'latch free' are seen on 12c (either following an upgrade from an earlier version or a new install)
- Checking in AWR report, the latch statistics section show high contention for "Result Cache: RC Latch" even though the RESULT_CACHE_MODE is set to MANUAL.
- All the sql using the result cache turned out to contain DS_SVC hints and are part of dynamic statistics activity. For example :
New install or upgrade to 12c from lower versions.
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